1. Field of the Invention
The present invention relates to a clamping device and, more particularly, to a clamping device for a weld seam-backing member.
2. Description of the Related Art
Many welding techniques have been developed and generally utilize high temperature and/or high pressure to fill molten welding flux in a welding gap between two work pieces that become joined after the welding flux cools.
FIG. 1 of the drawings illustrates a weld seam-backing member 2 (backing member hereinafter) for preventing overflow of molten welding flux S during welding and for providing a neat appearance after welding. The backing member 2 is adhered by a tape 21 to bottom sides of two work pieces 1 to be welded together. The welding member 2 is made of heat-resistant material such as ceramics that will not melt or join the welding flux S during welding. A welding gap 11 between two work pieces 1 is aligned with an arcuate groove 22 in an inner face of the backing member 2 and, thus, covered and sealed by the backing member 2. Thus, the welding flux S is kept in the welding gap 11 without the risk of loss. However, it is difficult for a welder to fix the backing member 2 in the right position at the first time, for the eyesight of the welder is obstructed by the tape 21 such that the arcuate groove 22 cannot be precisely aligned with the welding gap 11. Namely, the welder has to tear off the tape 21 in the incorrect position and redo the pre-welding job until the arcuate groove 22 of the backing member 2 is aligned with the welding gap 11. The pre-welding job becomes more difficult when the welding gap 11 is relatively long. The welding efficiency is, thus, low. Furthermore, the adhesion of the tape 21 deteriorates when the temperature rises due to welding, leading to the risk of loosening or falling of the backing member 2 before the welding flux S in the welding gap 11 cools and takes shape. Furthermore, toxic gas with unpleasant odor is generated when the adhesive 211 on the tape 21 is heated during welding, causing hazard to human health, which is particularly severe when in a space that is isolated or having poor ventilation. Furthermore, the tape 21 is generally made of aluminum foil and, thus, not recyclable after use. Pollution of environment occurs if the used tape 21 is not properly handled.